#pragma once
#include<iostream>
#include<string>
#include<assert.h>
#include<vector>
using namespace std;

namespace shen
{
	class string
	{
	public:
		using iterator = char*;
		using const_iterator = const char*;
		//string();
		string(const char* str = "");
		string(const string& s);
		~string();

		void reserve(size_t n);
		void push_back(char ch);
		void append(const char* str);
		string& operator+=(char ch);
		string& operator+=(const char* str);

		void insert(size_t pos, char ch);
		void insert(size_t pos, const char* str);
		void erase(size_t pos, size_t len = npos);

		size_t find(char ch, size_t pos = 0);
		size_t find(const char* str, size_t pos = 0);

		char& operator[](size_t i)
		{
			assert(i < _size);
			return _str[i];
		}

		const char& operator[](size_t i) const
		{
			assert(i < _size);
			return _str[i];
		}

		const char* c_str() const
		{
			return _str;
		}

		iterator begin()
		{
			return _str;
		}

		iterator end()
		{
			return _str + _size;
		}

		const_iterator begin() const
		{
			return _str;
		}

		const_iterator end() const
		{
			return _str + _size;
		}

		size_t size() const
		{
			return _size;
		}

		string& operator=(string s);


		string substr(size_t pos = 0, size_t len = npos);

		void clear()
		{
			_str[0] = '\0';
			_size = 0;
		}

		void swap(string& str);

	private:
		char* _str = nullptr;
		size_t _size = 0;
		size_t _capacity = 0;

	public:
		static const size_t npos;
	};

	bool operator==(const string& lhs, const string& rhs);
	bool operator!=(const string& lhs, const string& rhs);
	bool operator>(const string& lhs, const string& rhs);
	bool operator<(const string& lhs, const string& rhs);
	bool operator>=(const string& lhs, const string& rhs);
	bool operator<=(const string& lhs, const string& rhs);

	ostream& operator<<(ostream& os, const string& str);
	istream& operator>>(istream& is, string& str);
	istream& getline(istream& is, string& str, char delim = '\n');
}